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Greasecar

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A greasecar is an automobile that has been converted to run on straight vegetable oil (SVO) by installing a coolant-heated auxiliary fuel tank.

Process

The vehicle heats up the vegetable oil while burning diesel or Biodiesel from the stock fuel tank. Some systems require the driver to switch to the vegetable oil supply when he/she thinks the oil may be warm enough to combust, other systems perform these functions automatically using an electronic control module. The driver must remember to purge the fuel system of vegetable oil before shutting the car off for an extended period of time. If vegetable oil is allowed to cool in the injectors, it will become too thick to burn properly in the engine and will prevent the engine from being restarted without being warmed. Some systems are equipped with an alarm preventing the user from neglecting to purge the system.

Fuel

Used vegetable oil can be obtained for low or no cost from many restaurants including diners, Chinese food, Middle Eastern food, fast food, Mexican food, etc. Waste oil must be filtered to at least 5 micrometers and dewatered prior to use, while this is not difficult, it must not be overlooked. This can be done with the use of various filtering methods for SVO available for free online. Simply hanging bag filters over a bucket or pumping waste oil through home water filters is not sufficient and should be avoided.

Biodiesel

Straight vegetable oil (SVO) is not the same as Biodiesel. Biodiesel is created through a process called transesterification in which the vegetable oil molecule (triglyceride) is changed on a molecular level, lye is used to cleave the glycerine molecule from the triglyceride and the monoesters are stabilized with an alcohol - either methanol or ethanol. Any diesel vehicle can use biodiesel without major changes, although most produced before about 1996 will need to have the fuel lines and fuel system seals replaced with Viton materials. Biodiesel is also not stable below 40°F and will gel in the filter, tank and fuel lines. Straight vegetable oil (SVO) is nothing but vegetable oil, but must be heated to a minimum of 160°F before the fuel injectors can atomize it finely enough to burn completely. Since the engine must be started and warmed on a conventional fuel, a well designed SVO system utilizing waste engine heat to warm the oil can function seamlessly to well below -30°F.

Conversion

Various companies have offered conversion kits for a number of years. Some kits use engine coolant only as the heat source for the "grease" while others have attempted to utilize electric heat as well.

Heated fuel lines, filters and final fuel heat exchangers are required to burn vegetable oil in an engine designed to consume diesel. In a conventional diesel engine, vegetable oil must be heated to approximately 160°F before injection and the engine must be at operating temperature before any vegetable oil is used (to prevent lubricating oil contamination). For this reason, many choose systems based on coolant heating rather than inefficient electric heating of the oil, as once the engine is at operating temperature, there is sufficient waste heat transported by the coolant to heat the oil. Suppliers usually offer good FAQ's, forums and knowledge bases on the subject.

See also

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